Patent Application
20250146483
The present invention relates to gas compressors and inlet and discharge valve systems for such.
In various machines such as heat pumps, compressors are employed. Many heat pumps have a gas/vapor compressor as a core component. More specifically, for the vapor compression cycle, which is commonly used for, among other, residential heat pumps, refrigerators and air conditioning systems in cars, as well as for industrial heat pumps, the compressor is a central component. The main advantages of using heat pumps as opposed to conventional boiler or furnace systems, is that heat pumps generate several more times the heat than the power which is required to drive them, thereby increasing energy efficiency, and in many cases also improving economics of operation. In addition, for cases where heat pumps can effectively replace fossil-fuelled heat sources, a substantial reduction in climate gas emissions can also be achieved. As reduction in climate gas emissions becomes more and more important, the need for new and further heat pump technologies, which can cover new and further applications, and especially applications within different industries, the need for new and better compressor types is also increasing.
There are two main classes of compressor devices used for heat pumps: flow devices (often implemented as centrifugal compressors), and positive displacement devices, with the latter being available in a great variety of different devices based on several different geometrical principles, for example: screw compressors, scroll compressors, vane compressors and reciprocating/piston compressors. Each type has its own advantages and disadvantages, which will not be described in further detail here.
Common to all compressor types, is that they operate on a working fluid, also commonly referred to as a refrigerant, or simply gas. In some examples, the working fluid may be a condensable gas. In some examples the working fluid never changes phase, and hence the working fluid is only operated in a gaseous state. Throughout the present disclosure, any working fluid in any phase, including but not limited to: partly liquid; gaseous; and supercritical is intended when referring to the working fluid.
In the example described herein, the compressor is of the piston-type (also commonly referred to as a reciprocating compressor). However, it should be noted that the present disclosure is not limited to only piston-type compressors, and that it may be equally relevant and useful to other types of compressors.
The performance of heat pump compressors, and more specifically gas/vapor compressors, is mainly a result of the three characteristics:
Mechanical efficiency is primarily a consequence of internal, mechanical friction, or rather, a lack thereof. Volumetric efficiency is primarily a consequence of the internal, so-called dead volume (also called clearance volume, in the compressor's working chamber, i.e. the minimum achievable internal volume in the cylinder of a working chamber of a compressor during compression). Lastly, the isentropic efficiency is mainly a consequence of the effectiveness of the gas exchange processes, which include the suction process and the discharge process.
Beyond this, there are further factors that affect the aforementioned characteristics, such as thermal leakage/undesired heat exchange through internal surfaces, e.g., a cylinder wall, which affects the isentropic efficiency, and gas leakage past sealing elements etc., which affects the isentropic efficiency as well as the volumetric efficiency.
In the following, and to explain the principles of operation in an easier way, a reciprocating compressor with a conventional crankshaft is disclosed. In principle, the compressor operation is simple, and consists of four principal processes (or steps) that are performed cyclically. For piston compressors, these are performed once per revolution of the crankshaft:
The suction and discharge processes comprise the gas exchange processes, during which a working fluid, normally in its gaseous/vapor form, is either sucked into or discharged out of the cylinder. Again, this assumes a piston compressor, however, the very same processes also take place in all other positive displacement machines. For piston compressors in general, the gas exchange processes are governed by the suction and discharge valves: the suction valve controls the inflow of new, uncompressed gas into the cylinder during the suction process, while the discharge valve controls the outflow of compressed gas during the discharge process.
Compressors can have one or more cylinders, and each cylinder has its corresponding set of suction and discharge valves, and the suction/discharge valves can each in turn also consist of multiple valves working in parallel, as is quite common. In conventional compressor designs, the suction/discharge valves are usually in the form of a so-called reed valve, which constitutes a simple, yet effective principal component for many compressor applications.
Reed valves in principle comprise at least a valve plate or a valve port section with a reed element (also called a reed valve blade) and a retainer (sometimes also called a stop plate). The reed element is usually in the form of a thin metal sheet, which sometimes is also made from a spring material, with the reed element performing the actual opening and closing of the valve, by covering or uncovering port openings, slots or similar in the valve plate or valve port section. Sometimes an independent spring element is provided, which is made to continuously push and thus provides a force on the reed element in the closing direction. This is to aid in closing of the valve, and to prevent flow through the valve when it should otherwise be closed. The retainer can typically be a curved, relatively stiff sheet metal piece, which is shaped to let the reed element “roll” against its curved surface, as to limit the movement of the reed element and thus to guide it, and also to prevent damage that could otherwise be caused by excessive bending during operation. Other times the retainer is in the form of a retainer plate, which is fixed at a certain distance from the reed element, and often with a spring element in between. The principal function is the same, but the designs can vary. The fundamental characteristic of reed valves is that they are passively operated, meaning that they open and close only due to a pressure differential (or lack thereof) across the reed element in the opening direction.
Reed valves are compact and lightweight, their design is generally simple, and they provide for easy and affordable manufacturing. However, reed valves have some drawbacks for certain applications: It is difficult to design reed valves with as effective flow areas as for certain other valve types, and it is also difficult to design a compressor with a very low dead volume, especially when the suction valve is of the reed type. The consequence of this is that compressors equipped with reed valves usually have higher dead volumes and smaller effective flow areas than necessary. This in turn results in lower volumetric and isentropic efficiencies, respectively.
Moreover, and as mentioned above, for reed valves to properly close during operation, they are usually provided with a spring force in the closing direction, either by making the reed element itself out of a spring material, or by providing a separate spring element that pushes on the reed element.
Further, reed valves often suffer from so-called valve flutter under certain circumstances, during which the reed element will be exposed to excessive stress, sometimes leading to fatigue or other types of deformation with resulting damage, and in the worst-case catastrophic breakdown. This typically happens in certain frequency ranges, which for a compressor translates into specific speed ranges due to the cyclic operation. To overcome this, a stiffer spring or thicker reed material is sometimes used, and this leads to increased fluid flow resistance, which again leads to flow losses and corresponding reduction in the isentropic efficiency of the compressor.
Modern refrigeration and heat pump systems often use modern synthetic working fluids of the so-called 4th generation. These typically encompass hydrofluoroolefins (HFOs) and hydrochlorofluoroolefins (HCFOs). One difference between these and other fluids is in that their densities are often high for typical conditions that are present in a refrigeration or heat pump system. Especially for industrial heat pumps in the high-temperature category, the relevant modern working fluids have densities during operation in a typical range from 30-100 kg/m3 or even higher under relevant operating conditions. Compared to other fluids, this is very high, and this also means that valve performance becomes even more critical in terms of maximizing efficiency and performance. Because of, among other, the high densities, the pressure drops across valves, ports, pipes and other in a heat pump system will usually increase, leading to increased losses, and hence there is a substantial potential performance gain is to be achieved if valve performance can be improved.
Poppet valves are extremely common, they are used in a great variety of applications (for example in combustion engines), and they have a long history and are widely proven and accepted by the industry. Also, there is widely available, low-cost manufacturing of poppet valves around the world.
Since poppet valves are usually actively controlled through mechanical means such as camshafts, cam followers, pushrods and rocker arms, they can be opened actively without causing substantial pressure drops as can otherwise apply to reed valves. Also, their opening and closing timing can be made completely independent from the differential pressures across them, leading to useful flexibility in controlling the gas exchange processes for a compressor.
Further, the flow characteristics of poppet valves are generally very good, primarily due to a geometry that provide little flow resistance, which also applies to denser fluids. They are used in a great number of different applications, spanning from heavy-duty diesel engines to hydraulic circuits, and there is vast empirical experience and knowledge about their workings, limits, and performance in general. Flow characteristics of poppet valves and other properties such as durability have been extensively proven for many years.
UK patent document GB2416196A discloses a valve control system for a reciprocating gas compressor having at least one suction valve between a gas supply and a compressor cylinder. The suction valve opens and closes automatically in response to pressure in the cylinder but has a locking assembly which holds it in the open position for a selected period after it has opened, in synchronisation with the piston strokes of the compressor. This allows gas to enter and exit the compressor via the suction valve during the cycle for which the valve is open so that heat is removed along with the gas thus allowing the cylinder chamber to cool. The valve may be a disk or reed valve and the locking assembly may be electromagnetic or pneumatic. The compressor may have a heat regenerator mounted within the compressor cylinder for enabling transfer of heat out of the cylinder.
US patent document US2019003604A1 discloses a valve assembly including a seat plate having a top surface and a bottom surface, a plurality of first valve modules arranged in a first level relative to the seat plate such that a first seating face of each of the plurality of first valve modules is substantially co-planar with a first plane that is substantially parallel to at least one of the top surface and the bottom surface of the seat plate, and at least one second valve module arranged in a second level relative to the seat plate such that a second seating face of the at least one second valve module is co-planar with a second plane that is substantially parallel to the first plane, wherein the second plane is offset from the first plane by a first distance.
US patent document U.S. Pat. No. 4,370,103A discloses a piston pump mechanism for use in positive pressure and vacuum pumping systems for pumping various gases such as air, freon, natural gas, etc. The pump mechanism incorporates an inlet and discharge valve system that substantially eliminates any unpurged or unswept volume of gas within a pump cylinder during each reciprocating stroke of the pump piston. The pump mechanism also incorporates a control spool that floats within a pump head and has a sealed flexible interconnection with the discharge valve that allows the discharge valve to seek optimum seating engagement about the entire periphery of the cylinder. The valve control spool may be pressure balanced or controllably unbalanced, as desired, for influence of the discharge valve. The spool also provides for inlet of gas to an inlet valve that may be incorporated into the discharge valve.
International patent document WO2006115348 discloses intake and exhaust valves for a cylinder type air compressor. The intake valve includes a valve body having a plurality of intake ports, a movable shaft elastically installed in the valve body to open and close the intake ports, a packing for elastically supporting the outer surface of a valve head of the movable shaft when the movable shaft is moved upwards and downwards to reduce striking noise, and an elastic support element for elastically supporting the lower end of a stopper. The exhaust valve includes a plurality of exhaust ports defined in the valve body around the intake ports to be arranged in a circumferential arrangement centered around the movable shaft, and a ring-shaped movable opening and closing element elastically supported to open and close the plurality of exhaust ports.
UK patent document GB2396667A discloses a reciprocating gas compressor is described operating according to an extended cycle of 4, 6 or more strokes, wherein the first two strokes are sequential induction and compression strokes using a low pressure gas as working fluid and compressing it to a high pressure gas, and the remaining strokes are pairs of sequential filling and emptying strokes using more of the low pressure gas as heat transfer fluid for transferring heat from inside the gas compressor to outside the gas compressor. The gas compressor also contains a heat regenerator for absorbing heat from the compressed gas and releasing heat to the heat transfer fluid.
US patent document US 2003/030226 A1 relates to the use of elastomers with the sealing element of reciprocating gas compressor valves to increase the reliability of the gas tight seal within the reciprocating gas compressor valve and to increase the useful life of reciprocating gas compressor valve. The elastomeric material is either used as a coating layer on the sealing element of the reciprocating gas compressor valve, or as the entire sealing element. The elastomeric material acts as a cushion to reduce the wear on the sealing element, provides a superior gas tight seal, and is more tolerant of entrained dirt or liquids in the gas stream thereby increasing the operable life of the reciprocating gas compressor valve.
Chinese patent document CN 111022293A relates to a trans-critical reciprocating piston compressor taking CO2 as a refrigerant.
At least one aim of the present invention is to obviate or at least mitigate one or more drawbacks associated with the prior art.
According to a first aspect of the invention, there is provided a reciprocating compressor comprising: a suction valve; a discharge valve; and a working chamber; wherein the suction valve is configured to provide fluid communication between a suction channel and the working chamber and the discharge valve is configured to provide fluid communication between the working chamber and a discharge channel; wherein the suction valve comprises at least one non-self-actuated valve and the discharge valve comprises at least one self-actuated check valve.
Embodiments of the present invention can be advantageous in that they may combine some of the best features of non-self-actuated valves and self-actuated valves to create an improved compressor. This may be particularly so when the compressor is in the form of heat pump and refrigeration compressors.
Embodiments of the invention have been based upon the inventors' efforts in realising that the largest penalty in performance is often seen during the suction process of a compressor. During this process, the fluid flow direction is into the working chamber, and during compression the pressure differential is in the suction valve's closing direction, and poppet valves are therefore considered a feasible alternative to reed valves. However, for the discharge process, poppet valves are not as suitable, since the direction of pressure is in the opposite direction to the valve's closing direction, and hence greater measures are sought in various embodiments by the inventors to provide poppet discharge valves that are effective and can manage the pressure differential also when closed.
Furthermore, the inventors have considered that the need for higher valve performance is generally not as great for the discharge process as for the suction process, among other reasons because for reciprocating compressors, the discharge process happens when the piston is approaching top dead centre (TDC), and that is when the volumetric flow becomes lower due to the retardation and hence decreasing instantaneous speed of the piston(s), which again determines the volumetric fluid flow and flow velocity out of the discharge port. Therefore, embodiments using poppet valves or similar for the suction valve system and reed valves or similar for the discharge valve system can provide compromise with good and improved overall performance.
The self-actuated check valve may for example comprise one or more of: a reed valve; a plate-valve; self-actuated poppet valve; self-actuated ball check valve.
The non-self-actuated valve may for example be one or more of: a poppet valve; a rotary valve; a piston valve; a slide valve; a spool valve. The non-self-actuating valve may be one or more of: mechanically controlled; pneumatically controlled; electrically controlled; hydraulically controlled.
The reciprocating compressor may further comprise: a compressor block having at least one cylinder with a piston arranged to reciprocate therein; and at least one cylinder head; wherein the suction valve is arranged in the cylinder head.
The suction valve may be located on a longitudinal centre axis of the at least one cylinder.
The at least one cylinder head may comprise a valve plate.
The at least one cylinder may comprise a first cylinder with a first piston arranged to reciprocate therein and a second cylinder with a second piston arranged to reciprocate therein; the at least one cylinder head comprises a first cylinder head and a second cylinder head; and the first cylinder head is configured to mate with the first cylinder and the second cylinder head is configured to mate with the second cylinder.
The first and second cylinders may be arranged at around 90 degrees relative to each other to form a V-configuration.
The at least one discharge valve may be a plurality of self-actuated check valves.
The discharge valve may be arranged concentrically with the suction valve. The plurality of self-actuated check valves may each be concentric with the suction valve. The suction valve may be arranged such that the central axis of the suction valve is shared with the central axis of the at least one cylinder.
This can maximise the utilisation of the available valve area, and provide for a practical geometry. It should be noted that reed valves usually are limited in size due to the need to reduce their mass at the same time as requiring them to be flexible. Therefore, in reed-valve-based valve systems, many reed valves may be used in parallel. Reed valves may be conveniently configured in parallel. The valves may also conveniently be designed with a geometry that allows for circular patterns of arrangement, corresponding to the circular geometry of the compressor cylinder, and hence flow area utilisation can be maximized.
The discharge valve may be arranged such that the central axis of the discharge valve is shared with the central axis of the at least one cylinder.
The piston may be provided with at least one protrusion and the cylinder head is provided with at least one cylinder head recess, wherein the at least one protrusion and the at least one cylinder head recess are registered such that the protrusion will displace at least a portion of the volume of the cylinder head recess in use.
The at least a portion of the volume of the cylinder head recess may be at least 50% or at least 60%, or at least 70% of the recess volume, or a majority of the cylinder head recess volume.
The at least one protrusion may be a plurality of protrusions and the at least one cylinder head recess is a plurality of cylinder head recesses.
The piston may be provided with at least one piston recess which is shaped and configured to receive a non-self-actuated valve in use.
The piston recess may be configured such that in use the non-self-actuated valve will displace at least 50% or at least 60%, or at least 70% of the piston recess volume, or a majority of the piston recess volume.
This can provide an additional advantage in that the volumetric efficiency of the compressor can thus be further optimised. This advantage is not available when using passive, reed-valve-based valve systems only. The reason is that for suction valves using reed valves, the requirement for having a retainer plate or a stop plate makes it impossible to displace this portion of the dead volume, since the dead volume caused by the retainer/stop plates is hidden on their “back side”, away from the piston, and thus cannot be displaced.
The suction channel may comprise: a first portion formed in the compressor block; and a second portion formed in the at least one cylinder head; wherein the first and second portions are configured to mate at a connection to form a fluid passage between the first portion and the second portion for delivering working fluid to the working chamber in use. Since the suction channel will always see the lowest temperatures compared to the discharge channel, the suction channel can be designed to be part of a compressor block casting, and thereby additional pipes, sealings and flanges can be eliminated, as well having the option to form this part of the suction channel to one's needs. A combination of good flow characteristics as well as reduced number of parts, including potentially leakage-prone sealings, can then be avoided.
The first portion of the suction channel may comprise a fluid entry path adjacent the connection when the first and second portions are mated in use, wherein the fluid entry path is configured to direct fluid at an angle of between 20 degrees and 80 degrees relative to a normal on a cylinder centre axis. The angle may be around 45 degrees.
By carefully designing the fluid entry path, an improved flow path can be achieved. This flow path is fluid-dynamically optimised and provides reduced pressure drops by promoting shallower turns in the fluid flow path.
The first portion may comprise a buffer reservoir. The buffer reservoir may have a substantially larger volume than the volume of the working chamber such that in use when working fluid is sucked out of the buffer reservoir to fill the working chamber, there is not a substantial pressure drop in the buffer reservoir.
The working chamber may be a first working chamber and the suction channel a first suction channel; wherein the compressor further comprises a second working chamber and a second suction channel; the first and second suction channels join to form a combined suction channel comprising an inlet for the compressor receiving working fluid therethrough.
This is typically advantageous because it reduces the number of parts in the compressor and importantly it reduces the number of sealing surfaces.
The inlet may comprise a manifold.
According to a second aspect of the invention, there is provided a heat pump comprising the reciprocating compressor according to the first aspect of the invention.
The heat pump may be a high-temperature heat pump capable in use of supplying output temperatures above 55 degrees Celsius or above 80 degrees Celsius or above 90 degrees Celsius or above 100 degrees Celsius or above 110 degrees Celsius or above 120 degrees Celsius or above 130 degrees Celsius or above 140 degrees Celsius or above 150 degrees Celsius or above 160 degrees Celsius or above 170 degrees Celsius or above 180 degrees Celsius or above 190 degrees Celsius or above 200 degrees Celsius or above 210 degrees Celsius or above 220 degrees Celsius or above 230 degrees Celsius or above 240 degrees Celsius or above 250 degrees Celsius.
According to a third aspect of the invention, there is provided use of a reciprocating compressor according to the first aspect of the invention in a heat pump.
According to a fourth aspect of the invention, there is provided a method of operating a reciprocating compressor according to the first aspect of the invention, comprising the steps of: sucking working fluid into the working chamber via the at least one non-self-actuated valve; and discharging working fluid from the working chamber via the at least one self-actuated valve.
According to a fifth aspect of the invention, there is provided a reciprocating compressor comprising: a suction valve; a discharge valve; and a working chamber; wherein the suction valve is configured to provide fluid communication between a suction channel and the working chamber and the discharge valve is configured to provide fluid communication between the working chamber and a discharge channel; the compressor further comprising: a compressor block having at least one cylinder with a piston arranged to reciprocate therein; and at least one cylinder head; wherein the suction valve is arranged in the cylinder head, wherein the suction channel comprises: a first portion formed in the compressor block; and a second portion formed in the at least one cylinder head; wherein the first and second portions are configured to mate at a connection to form a fluid passage between the first portion and the second portion for delivering working fluid to the working chamber in use. The suction valve may comprise at least one non-self-actuated valve and the discharge valve may comprise at least one self-actuated check valve. The reciprocating compressor of the fifth aspect of the invention may have any one or more further features as set out in relation to the reciprocating compressor of the first aspect of the invention.
According to a sixth aspect of the invention, there is provided a method of using a reciprocating compressor according to the sixth aspect of the invention.
According to a seventh aspect of the invention, there is provided a reciprocating compressor comprising a working chamber and a buffer reservoir, wherein the buffer reservoir has a substantially larger volume than the volume of the working chamber such that in use when working fluid is sucked out of the buffer reservoir to fill the working chamber, there is not a substantial pressure drop in the buffer reservoir. The reciprocating compressor may further comprise: a suction valve, a discharge valve, and a working chamber, the suction valve being configured to provide fluid communication between a suction channel and the working chamber and the discharge valve being configured to provide fluid communication between the working chamber and a discharge channel. The suction valve may comprise at least one non-self-actuated valve and the discharge valve may comprise at least one self-actuated check valve. The reciprocating compressor may have any one or more further features as set out in relation to the reciprocating compressor of the first aspect of the invention.
According to an eighth aspect of the invention, there is provided a method of operating a reciprocating compressor according to the seventh aspect of the invention, comprising a step of sucking working fluid into the working chamber from the buffer reservoir.
The prior art and embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
Working fluid inflow is controlled and admitted from the suction channel 40 into the working chamber 251 through a suction valve 110, and working fluid outflow is controlled and admitted out of the working chamber 251 to the discharge channel 50 through two discharge valves 120. As can clearly be seen in
The valves 110, 120 shown in
Working fluid inflow is controlled and admitted from the suction channel 40′ into the working chamber 251′ through a suction valve 110′, and working fluid outflow is controlled and admitted out of the working chamber 251′ to the discharge channel 50′ through discharge valves 120′. As can clearly be seen in
The suction valve 110′ of the example shown in
Still referring to
Referring now to
As working fluid enters the common manifold 43″ of the suction channel 40″ at the rear of the compressor 1″, the working fluid travels towards the front of the compressor 1″ in the direction of the viewer in
In other exemplary compressors (not shown) comprising multiple cylinders 250″, there may be provided a single common manifold 43″ for receiving working fluid from the auxiliary piping. In this connection, each cylinder 250″ may be arranged to receive working fluid from the common manifold 43″ through a splitting of the working fluid between the common manifold 43″ and each of the buffer reservoirs 44″. This not only reduces the number of external connections that otherwise need to be made (e.g. one for each cylinder head's 10″ suction channel 40″), but also greatly reduces the number of seals/gaskets needed, since the connection 42″ is sealed using the same seal as would be required anyway for the interface between the cylinder head 10″ and the compressor block 20″, as will be explained in more detail later.
Still referring to
Referring now to
As working fluid enters the common manifold 43″′ of the suction channel 40″′ at the rear of the compressor 1″′, the working fluid travels towards the front of the compressor 1″′ in the direction of the viewer in
Reducing the angle 46″′ which the working fluid must turn at in the buffer reservoir 44″′ results in the fluid flow path 41″′ taking a smoother path through the compressor 1″′, which may result in a reduced pressure drop as the working fluid moves from the common manifold 43″′ to the fluid inlet channel 45″′, thereby resulting in increased performance of the compressor 1″′.
The cylinder head 10″′ may in some examples comprise a valve plate (not shown in
Referring firstly to
A working fluid has typically undergone pre-heating, evaporation and superheating in one or more heat exchangers (not shown) before entering the compressor 1″″ typically through a pipe, a manifold, or a network of pipes (not shown). The working fluid enters the compressor 1″″ through a single common manifold 43″″, thereby providing only one entry point for the working fluid into the compressor 1″″. In the presently described example, as in previous examples, the common manifold 43″″ is arranged at the rear of the compressor 1″″. It will be understood that the front and rear of the compressor 1″″ may be reversed in other examples, and indeed that the common manifold 43″″ may be located centrally on the compressor in some examples rather than being at the front or the rear.
Still referring to
The first fluid flow travels from the first buffer reservoir 44A upwards towards the top of the compressor 1″″ through a first connection 42A and via a first fluid inlet channel 45A to a first working chamber 251A. In summary, in the presently described example, the working fluid travels across the compressor 1″″ and then travels upwards towards the top of the compressor 1″″ via the first buffer reservoir 44A.
When the first piston 240A expands the volume of the working chamber 251A while moving away from the cylinder head 10A, suction causes working fluid to enter the first working chamber 251A through a first suction valve 110A, which in the presently described example is a poppet valve.
By the rotary motion of the crankshaft 210″″, a translatory motion of the first piston 240A inside the first cylinder 250A is provided, cyclically bringing the pistons 240A “down” to bottom dead center (BDC) position, at which the suction process stops. The compressor 1″″ then starts to compress the working fluid in the first working chamber 251A until the working fluid has reached a pressure exceeding that of the pressure in a discharge channel 50A, and then the discharge process begins, as the first discharge valves 120A, which in the presently described example are reed valves, then open because of the differential pressure across their reed blades, as previously explained.
As previously discussed, the same steps are performed for the second piston 240B in the second cylinder 250B. The first discharge channel 50A may continue into a manifold, pipe or similar where a fluid connection may be made to the second discharge channel 50B such that the working fluid flows can be combined and the combined fluid flow may then be lead further to one or more heat exchangers (not shown), in which the working fluid is typically desuperheated, condensed and optionally subcooled. In other examples, one or more of these processes may be applied, or other processes may be applied to the discharged working fluid.
The first and second inlet valves 110A, 110B are actuated by conventional valve actuator mechanisms, the design and/selection of which will be well within the capabilities of a person skilled in the art.
The first suction channel 40A is partly in the first cylinder head 10A and partly in the compressor block 20″″ with connection of the two parts of the first suction channel 40A being provided by the first connection 42A.
In the presently described example, the working fluid in the first fluid flow stream travels across the compressor 1″″ and then travels upwards towards the top of the compressor 1″″.
Although the working fluid path is only described above with reference to the first buffer reservoir 44A, it will be appreciated that the second buffer reservoir 44B is also configured in a similar fashion to as described for the first buffer reservoir 44A. It will also be appreciated that in examples with further cylinders, such as sixteen cylinders, some or all of the buffer reservoirs may be as described above for the first buffer reservoir 44A.
Still referring to
Still referring to
The lubricant reservoir 30″″ is equipped with a plurality of lubricant heaters 301″″, that are embedded in a main block 300″″ of the lubricant reservoir 30″″. These heaters 301″″ can be activated upon relevant need through a standard control system (not shown).
The first discharge valve slots 142A provide fluid communication between the first working chamber 251A (shown in
In the cross-sectional view in
In the present invention, a first recess 141A is provided in the first valve plate 140A as can be seen in
Volumetric efficiency is an important performance factor of any compressor, and this is closely linked to the compressor cylinders' dead volume: The dead volume is the combination of non-displaceable (by the piston) volumes primarily caused by two factors. Firstly, the clearance volume needed to ensure that the piston does not collide with the cylinder head, valve plate or valves due to production tolerances, valve motion, varying gasket thicknesses etc., and secondly passive volumes that are required as part of ports, slots or other, due to the need to provide a certain material thickness to house these.
Referring again to
Referring now to
In any of the above-described examples, the suction channels 40′, 40″, 40″′, 40A, 40B, and/or discharge channels 50′, 50″, 50″′, 50A, 50B, may be formed during casting of the cylinder head 10′, 10″, 10″′, 10A, 10B and compressor block 20′, 20″, 20″′, 20″″, respectively.
The presently described compressors allow a lower pressure drop to be maintained across the suction valve during operation, thereby maintaining a higher efficiency of the compressor when utilizing more demanding working fluids, and especially those with a higher density.
The present disclosure describes poppet and reed valves. It will be understood that the reed valves may be replaced by any self-actuated check valve or valves and the poppet valve may be replaced by any non-self-actuated valve or valves. As non-limiting examples only, known arrangements of self-actuated check valves are now described briefly with reference to
As another non-limiting example, another self-actuated check valve 600 in the form of a plate valve is provided which is configured to move from a closed position shown in
As another non-limiting example, another self-actuated check valve 700 is provided which is configured to move from a closed position shown in
As previously mentioned, throughout the present disclosure, reference is made to reed valves and poppet valves. However, it will be appreciated that configurations using a reed valve or valves may be replaced by any self-actuated check valve or valves and configurations using a poppet valve or valves may be replaced by any non-self-actuated valve or valves. The self-actuated valves may be any of the non-limiting examples shown in
It will also be appreciated that “self-actuated” is intended to carry the standard meaning within the art. That is that self-actuated valves are passively opened and closed, i.e. they open and close in response to fluid pressure in the system rather than being driven by an external electrical or mechanical source provided for the purpose of opening or closing the valve. Similarly, “non-self actuated” is also intended to carry the standard meaning within the art, i.e. that the valve is actively driven, rather than opening and closing in response to fluid pressure in the system.
It will be understood that at the time of writing, the term “high-temperature heat pump” generally refers to the heat pumps capable of supplying output temperatures above 55 degrees Celsius. It will be appreciated by a person skilled in the art that the definition of “high-temperature” in this context may change over time, and it is foreseeable with advancements in technology that in the future “high-temperature” may be used to refer to heat pumps with an output temperature of above 80 degrees Celsius for example, or even higher.
In the above description there are several features of the described examples that are well-known to a person skilled in the art, and which have either been omitted or at least not described in detail for the sake of brevity. Further, although a preferred example comprises a heat pump compressor, and more specifically a heat pump compressor that utilises a condensable gas, the invention is not limited to this, and may be just as relevant for any other application requiring a compressor, for example an air compressor, natural gas compressor, CO2 compressor etc.
It will be understood that a plurality of non-self-actuated valves may together form a “suction valve”, i.e. there need not be one single non-self-actuated valve element forming the entire suction valve. Likewise, a plurality of self-actuated check valves may together form a “discharge valve”, i.e. there need not be one single self-actuated check valve element forming the entire discharge valve.
For example, as shown in the example described with reference to
| Number | Date | Country | Kind |
|---|---|---|---|
| 20220232 | Feb 2022 | NO | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/NO2023/050026 | 2/1/2023 | WO |
